GMC and Lexus have emerged as the top performers in J.D. Power and Associates' annual Customer Service Index (CSI) study, which measures satisfaction car owners have with service departments after getting maintenance or repair work done. Many automakers saw huge improvements this year in their CSI scores, which are based on a 1000-point scale. For the fifth consecutive year, Lexus topped all other luxury brands, while GMC took the mass-market-brand title from Mini.

The CSI survey is based on responses from about 91,000 owners and lessees of 2008-2012 model-year vehicles; the survey was conducted between October and December 2012.

Customer satisfaction at dealer facilities improved to a 797-point average for the 2013 CSI survey, up 10 points from last year. Seventy-seven percent of visits to service departments were for maintenance instead of for repairs, J.D. Power says, and a significant eight brands -- out of 30 total brands -- improved CSI scores by at least 20 points.

Perhaps the biggest luxury brand winner -- and loser -- is Land Rover. While the brand's 825-point score put it at the very bottom of the luxury brand chart, that score is a whopping 29 points higher than its performance last year. Behind Lexus this year were Cadillac, Jaguar, and Acura, in that order. Infiniti improved by 24 points this year to claim fifth place, and although Porsche claimed fifth place last year, the brand isn't included in this year's CSI survey results. J.D. Power reports that a sample collection process "resulted in [a] non-representative sample for the brand."The luxury brand average was 846 points, well above the mass-market brand average of 789 points. Scion, Nissan, Dodge, Mitsubishi, and Chrysler all improved their scores by 20 points or more, and the top 5 included GMC, Mini, Buick, Chevrolet, and Volkswagen, in that order. Jeep, Ram, and Dodge fill the bottom three slots on the mass-market brand chart, though the Chrysler brand scored a mid-pack rating.

@BlackDynamiteOnline Did you notice that your toyota and scion are almost at the bottom? Both well below all of GM's mainstream brands as well as Chrysler and Ford, but that must be a fluke (sarcasm).@BlackDynamiteOnline

@BlackDynamiteOnline While I would normally agree with you on this one BD, Toyota should take a little note... along with the myriad of other things that helped Detroit slowly drop from the top in sales and satisfaction, incompetent and argumentative service representation certainly didn't help the image. You can't tick off customers and hope to win them back every time.